This invention relates to immunomodulators.
Nonspecific immunotherapy usually involves the use of immunomodulating agents administered with the aim of either general stimulation of or general suppression of a person's immune system. General immunostimulation enhances the ability of the immune system to respond to various diseases, e.g., cancer, bacterial infections, and virus infections, and thus can be a useful treatment for these disorders.
One example of an immunostimulating agent is bestatin (N-[(2S, 3R)-3-amino-2-hydroxy-4-phenylbutyl]-L-leucine), an amino acid derivative isolated from culture filtrates of Streptomyces olivoreticuli. A synthesis of bestatin is described in Nighizawa et al., 36 J. Antibiotics 695, and in British Pat. No. 2,037,754.